The present invention relates generally to a computerized ultrasound-laser surgical device and method for imaging internal tissue areas and irradiating selective regions of the tissue area with laser to surgically remove unwanted tissue residing in the imaged tissue area. More specifically, the present invention provides a catheter having an ultrasound transducer and associated electrically wiring conducted through a sidewall thereof and a plurality of optical fibers provided in the lumen of the catheter for conveying laser light from an external laser source to the tip of the catheter. The ultrasound and the laser are connected to a computer system which is used to display ultrasonic images of internal tissue areas within the patient's body which is used to display ultrasonic images of internal tissue areas within the patient's body which convey tissue information to the physician. By interacting with the computer system, the physician is able to selectively irradiate and destroy unwanted tissue from the ultrasonically displayed area by controlling the direction, duration and intensity of the laser burst.
The use of laser radiation to destroy certain types of structures or tissues has become increasingly accepted. Conventional surgical procedures often require radical invasion of healthy body tissue, whereas the known laser surgical techniques permit non-open surgery in which the laser is applied to selected tissue through a light pipe, cystoscope or laser probe. U.S. Pat. No. 4,672,963 (hereinafter the "Barken Patent") issued to Israel Barken, the inventor hereof, on Jun. 16, 1987, which is hereby incorporated by reference thereto, discloses an apparatus and method for computer controlled laser surgery which introduces an ultrasound probe and a laser probe into the body of the patient and destroys unwanted tissue by visualizing the tissue region though ultrasonic imaging and irradiating a selected tissue area to be destroyed. U.S. Pat. No. 4,576,177 (hereinafter the "Webster Patent) issued to Wiltos W. Webster, Jr. on Mar. 18, 1986 discloses a catheter for removing arteriosclerotic plaque. The catheter disclosed in the Webster Patent consists of a single optical fiber for transmitting laser irradiation and an ultrasonic transducer mounted at the tip of the catheter for transmitting and receiving ultrasonic signals.
An important distinction between the Barken Patent and The Webster patent is the Webster Patent utilizes a rather arcane ultrasound transducer/receiver sensitive only to ultrasonic signal echoes which produce an electronic signature, on an oscilloscope, of the tissue character and the blood flow velocity between two selected distances from the catheter tip. In Barken, however, it is taught that an ultrasound probe may be used to display a visual image of the internal tissue area. An important advantage of the Barken system, therefore, is that it eliminates the need for electronic signature interpretation to properly characterize the tissue while permitting the physician to actually visualize the pertinent tissue area. To further facilitate surgical accuracy, Barken teaches the use of a computer system to construct real time three-dimensional images of the tissue area to be irradiated and to store tissue and laser irradiation data and control the intensity and duration of irradiation.
Despite the significant advances in the art provided by the Webster and Barken Patents, directional control of the laser firing with respect to the tissue to be irradiate is problematic. The Webster Patent teaches that is known to mount the optical fiber in the central opening of the ultrasound transducer. In Webster, the ultrasound transducer is angularly mounted on the tip of the catheter. A microlens is mounted within the central opening of the transducer and optically coupled to the optical fiber to change the direction of the laser irradiation to about the center of the transmitted ultrasonic signal. Thus, the catheter of Webster is capable only of unidirectional laser firing and requires physician intervention to redirect the laser. Similar to the Webster catheter, all known laser surgical apparatus permit only single-direction laser firing.
Accordingly, there are several disadvantages associated with the apparatus disclosed in the Webster Patent. Specifically, ultrasonic imaging of the tissue area is not provided thereby requiring the physician to interpret electronic signals rather than images, the single laser fiber permits only single-direction laser firing and requires manual manipulation of the catheter to change the laser firing direction and there is no computer system to store tissue information and control laser firing to preserve healthy tissue and destroy only unwanted tissue. The Barken Patent provides a computer system to process information from the ultrasound and display real-time constructed three-dimensional images on an associated monitor and control laser activation and power, and, therefore, represents a major advancement over the Webster Patent. However, the Barken Patent is silent on any specific apparatus to incorporate both an ultrasound probe to provide real time tissue images and a laser probe which is capable of multi-directional firing without requiring manual manipulation to adjust laser firing direction.